JP2538859B2 - Variable speed pumped storage system control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control method of a variable speed power generation system for operating an induction machine with secondary excitation at an arbitrary rotation speed, and particularly to an automatic frequency of power generation and pumping. The present invention relates to an operation control method suitable for stable control to a target value during control (AFC) operation.

[Background of the Invention]

A conventional pumped storage power generation system is not able to adjust the load during pumping, changes in the power generation required by the grid during power generation operation, and pumping operation, in particular the pumping head, causes the system efficiency to increase. The drawback was that it changed.

For this reason, research is being conducted to operate the above system at the highest efficiency regardless of the power generation and the head.
The trend of the research is 2
A so-called variable speed power generation system, which operates as an induction machine with secondary excitation and operates at a rotational speed other than the synchronous speed, is being adopted. By adopting such a variable speed power generation system, it becomes possible to operate the system at the highest rate regardless of power generation and head. Therefore, various studies have been conducted to realize this variable speed power generation system.
This variable speed power generation system has already been introduced in the paper of National Conference of the Institute of Electrical Engineers of Japan in 1984, No.553, "Variable speed operation characteristics of large capacity synchronous motors", but what is the specific control method? Not touched.

[Object of the Invention]

An object of the present invention is to provide a control device for a variable speed pumped storage power generation system that can be operated with high efficiency in various operating states of power generation and pumped water and that can be stably controlled to a target value during AFC operation.

A control device for a variable speed pumped storage hydropower system of the present invention connects a water turbine to an induction machine having a secondary winding connected to an electric power system, operates the water turbine at a variable speed setting, and controls the secondary winding. In a control device of a variable speed pumped storage hydropower system including secondary excitation control of a wire with electric power of a slip frequency, an active power command value of input and output to and from the induction machine is input, and the active power command value is responded to. The output value of the water turbine indicates a rotation speed command value, which is obtained and output according to preset active power and characteristic data of the maximum efficiency rotation speed, and the actual lift is input to the actual lift and the active power command. Command calculation means (15) for obtaining and outputting a command value of the guide vane opening degree of the water turbine based on the value and the command value of the rotational speed
And a comparing means (24) for obtaining a difference between the rotation speed command value output from the command calculating means and the actual rotation speed of the water turbine, and the guide vane opening degree so that the difference in the rotation speed becomes zero or near zero. Correction means (25, 26) for correcting the command value, opening degree setting means (14) for outputting the set value of the vane opening degree to the turbine control means based on the corrected guide vane opening degree command value, Phase difference angle calculating means (16) for obtaining a difference between the active power command value and the actual power of the induction machine, and for obtaining a phase angle command value of the secondary excitation power required to bring the difference to zero or near zero. Voltage adjusting means (18) for setting the amount of secondary excitation required to make the terminal voltage of the induction machine the reference voltage that is the target of the system
And a secondary winding excitation amount setting means (17) for setting various amounts of excitation power of the secondary winding based on the set secondary excitation amount and the phase angle command value. And an exciting means (23) for exciting the secondary winding based on the amount of excitation.

Here, the operation of the present invention having the above configuration will be described.

First, in general, a variable speed pumped storage generator inputs and outputs the required active power, and thus it is natural to control the guide vane opening of the water turbine according to the active power.

However, the present invention has been made based on the finding that the turbine efficiency changes according to the output of the induction machine or the value of the input active power, and that the rotation speed at which the maximum efficiency is changed differs depending on the value of the active power. That is, the present invention sets the characteristic data of active power and maximum efficiency rotation speed in advance, obtains the maximum efficiency rotation speed corresponding to the command value of the input active power, and guides based on the obtained rotation speed. Since the vane opening is controlled, it is possible to always operate with high efficiency even if the active power command value changes.

Second, as a method of controlling active power, in addition to controlling the absolute value of the excitation voltage, in the case of an induction machine, since it is AC excitation, the phase of secondary excitation is controlled, that is, the phase difference. It is possible to control the corners to control the active power.
Further, it is conceivable to combine and control these two elements. In this respect, the present invention controls the phase difference angle based on active power for the following reason. As is well known, the active power P and the reactive power Q of the variable speed pumped storage generator connected to the grid can be expressed by the following equations, respectively.

Here, E ₁ is the output voltage vector of the variable speed pumped-storage generator, E ₂ is the system voltage vector when the system side is considered as an infinite bus, X is the reactance of the line between them, θ
Is the phase difference angle between the variable speed pumped storage generator and the infinite bus.

On the other hand, in the normal operating range of pumped storage power generation, the phase difference angle θ is small (for example, about 10 °), so if θ is changed in such a range, the reactive power Q hardly changes due to the difference between sin θ and cos θ. Moreover, only the active power P can be controlled.

In view of such characteristics, the present invention determines at least the difference between the active power command value and the actual power of the induction machine, and controls the phase of the secondary excitation power so that the difference becomes zero or near zero. It was decided. Thus, according to the present invention, the effective power P of the variable speed machine can be stably controlled with less influence on the system. As a result, AFC
The variable speed pumped storage generator can be stably controlled to the target value during operation.

In place of the phase difference angle calculating means (16), the difference between the active power designation value and the actual power of the induction machine is obtained, and the sum of the difference and the rotational speed difference is set to zero or near zero. The phase difference angle calculating means (16) for obtaining the required phase angle command value of the secondary excitation power may be used. According to this, since the difference in the number of rotations is added to the phase command value, the response speed of the active power P control is improved.

Example of Invention

FIG. 2 is a diagram showing an outline of the variable speed power generation system, which comprises three-phase windings on both the primary and secondary sides.

In the figure, 1 is a stator and 2 is a rotor. a ~
Reference numeral c is a stator a, b, c phase winding, and 6a to 6c are rotor a, b, c phase windings. If the rated frequency is f and the slip is s,
The speed of the rotor 2 is f (1-s), and by exciting the exciting winding of the rotor 2 at the frequency of the slip s, the rotating magnetic field generated by the rotor 2 rotates at zero slip (periodic speed). However, the velocity of the rotating magnetic field of the stator 1 becomes the same. Reference numeral 7 denotes a measuring unit that measures the number of rotations of the rotor 2.
The output from the slip detection unit 3 is taken in, and the detection unit 3
The slip frequency is detected and the detected signal is supplied to the voltage generator 4. The voltage generator 4 generates a voltage according to the slip frequency and excites the secondary winding.

By doing so, it is possible to always generate a voltage of the system frequency in the armature winding even when the operation is performed at an arbitrary rotation speed. That is, in the configuration of FIG. 2, the rotating magnetic field of the rotor is f (1-s) + fs = f (1), and an output at the rated frequency can be obtained regardless of slippage. In this method, the present embodiment is a method that can be stably controlled to a target value at any rotation speed during AFC operation of pumping and power generation.

FIG. 1 shows an embodiment applied to an operation control method of a variable speed power generation system according to the present invention, and shows a case where a variable speed machine is connected to a system for operation. Ten
Is an electric power system, and 1 and 2 are the same stator and rotor as in FIG. Static difference H and output command P ₀ are command value calculation circuit
When given to 15, the command value calculation circuit 15 calculates the guide vane opening command value H _v and the speed command value N ₀ in consideration of efficiency. The command value calculation circuit 15 calculates the speed command value N _0, and supplies the calculated value N ₀ to the comparison unit 24. This value
The difference between N ₀ and the actual rotational speed N is obtained by the comparison unit. Comparison section
The output from 24 is supplied to the correction unit 26 via the speed response governor 25. The target value H _v of the guide vane opening from the command value calculation circuit 15 is corrected by the signal input to one side of the correction unit 26. The output from the correction unit 26 is given to the opening degree setting device 14, and the opening degree of the guide vane is determined with a time delay of the opening degree setting device 14. The opening of the guide vane 13 of the water turbine is adjusted based on the output of the opening setter 14, and the opening and the static drop difference H
Based on the turbine characteristics, the rotor 2 connected to the turbine 12 rotates at the rotation speed N. Reference numeral 11 is a speed generator, and the speed is detected by the output from the generator 11. Reference numeral 19 is a current transformer, 20 is a voltage transformer, and the active power deriving unit 21 calculates active power based on the outputs from the current transformer 19 and the voltage transformer 20. 16 is a phase difference angle calculation unit of the secondary winding,
The phase difference angle calculation unit 16 calculates the phase difference angle based on the active power P output from the active power derivation unit 21 and the output command P ₀ . Reference numeral 17 is a setting unit that sets the amount of excitation of the secondary circuit, and 18 is a voltage adjustment unit that controls the voltage value of the amount of excitation. Reference numerals 23a, 23b, and 23c are phase shift units that shift the amount of excitation set by the setting unit 17 for use in the a, b, and c phases. 22a, 22b, 22c are excitation windings,
The excitation windings 22a, 22b, and 22c are excited in the a, b, and c phases with the amount of excitation that has been phase-shifted by the phase shift units 23a to 23c. In this way, the guide vane opening command H _v and the speed command N ₀ are given to the output command, and the guide vane opening H _v is targeted based on the difference between the actual rotational speed N and the target value N _0. Correct the value to suit the actual situation.

The present invention is intended to establish an optimum system of the phase difference angle control unit of FIG.

An embodiment of the present invention will be specifically described below with reference to FIG. FIG. 3 shows an example in which a so-called variable speed power generation system G ₁ , which can be operated at an arbitrary rotation speed by an induction machine with secondary excitation, is connected to the system 10 via a transmission line L and operated. It is a thing. A voltage transformer 20 and a current transformer 19 are installed on the power transmission line L.

Generally, a Francis turbine is used for a pumped-storage power generator, and the relationship between turbine output and efficiency is shown in FIG. This figure shows the turbine output on the horizontal axis and the efficiency on the vertical axis, and shows the number of revolutions as a parameter. P ₁ and P ₂ are turbine output, n ₁ and n ₂ are turbine efficiency, and N ₁ and N ₂ are rotational speed. The turbine efficiency is the ratio of the turbine output to the hydraulic energy that acts on the turbine. Further, if the loss of the induction machine including the stator 1 and the rotor 2 is ignored, the turbine output has a relationship corresponding to the active power P. The output P ₁ is the rotation speed N ₁ , the output P ₂ is the rotation speed N ₂ , and the maximum efficiency n ₁ , n _{2 at} each output
It shows that it becomes. Thus, depending on the output,
The number of revolutions at which the efficiency is highest is different, and the present invention seeks to operate at these highest efficiency points.

In FIG. 3, when the output command P ₀ required by the generator is given from the operating end T of the variable speed power generation system, the highly efficient operation is performed in consideration of the characteristics of the power generator and the water drop. As much as possible, the number of revolutions of the generator N ₀ , the guide vanes of the water turbine v
The opening degree H _{v of} is _calculated by the control command unit 100, and the operation is controlled so that the operation that meets these values can be performed. When a generator output reduction command is given in such a state, the number of revolutions will be adjusted by a previously given method so that the efficiency of the generator will be optimized based on the generator output and the water drop.
N ₀ and the valve opening H _v of the guide vane are obtained, and the rotation speed and the valve opening are controlled so that these target values are achieved, and efficient operation is performed.

On the other hand, the deviation of the generator speed from the rating is due to the excitation circuit _Ex
As described above, by using the slip frequency, the output at the rated frequency can be obtained as described above.

Next, a specific example of secondary excitation will be described. As shown in FIG. 1, the three-phase secondary excitation voltage is expressed as follows.

That is, the phase difference angle Δ among the functions for obtaining the excitation amounts of the a, b, and c phases by the command given from the operation end T of FIG.
Find δ. _Letting the excitation voltages of the a, b, and c phases be v _fa , v _fb , v _fc Is given. Where E: voltage value determined by slip and variable speed machine operating state, t: time, δ ₀ : phase angle determined by variable speed machine operating state, Δδ: phase angle controlled by output of control command unit and To do. When the control is performed using the above formula, the control command for the reactive power may be controlled by the voltage E, and the control command for the active power may be controlled by the phase angle Δδ.

In this embodiment, in the above formula, the active power is stably controlled to the target value during AFC operation.

Therefore, in the above configuration, it is necessary to control the phase angle (Δδ) of the exciting circuit to match the power with the target value. Therefore, active power is used as information for moving the phase angle. That is, the phase angle Δ
δ is expressed as Δδ = k ₁ (P−P ₀ ) ... (9). Here, P ₀ is a value immediately before the active power control command is given, P is an actual value of the active power, and k ₁ is a constant.

On the other hand, the turbine input is controlled by adjusting the valve opening of the guide vane. That is, as shown in FIG. 1, based on the result obtained from the target value N ₀ of the number of revolutions and the actual value N of the number of revolutions, the guide vane opening degree setting device 14 To control.

FIG. 5 is a diagram showing another embodiment of the present invention. According to this embodiment, the response at the time of control can be speeded up.

In FIG. 5, the output (N−N ₀ ) of the comparison unit 24 is given to the secondary winding phase difference angle calculation unit 16, and the phase difference angle Δδ is Δδ = k ₁ (P−P ₀ ) + k ₂ (N− N ₀ ) ... (4) Where N ₀ : target speed, N: actual speed, k ₂ :
It is a constant.

By doing so, the deviation of the number of revolutions (N-N ₀ )
Since the secondary winding phase angle Δδ can be controlled by the power deviation (P−P ₀ ), the target value can be controlled at high speed. Here, as P ₀ , a value before the command change may be used, or a value after the command change may be used.

〔The invention's effect〕

According to the present invention, the characteristic data of active power and maximum efficiency rotation speed is set in advance, the maximum efficiency rotation speed corresponding to the command value of the input active power is calculated, and the guide speed is determined based on this calculated rotation speed. Since the vane opening is controlled, it is possible to obtain a special effect of always operating with high efficiency even if the active power command value changes.

Also, since the difference between the active power command value and the actual power of the induction machine is calculated, and the phase of the secondary excitation power is controlled so that the error becomes zero or near zero, it affects the reactive power. The variable speed machine can be stably controlled according to the surplus or shortage of the effective power P command value, and as a result, the variable speed pumped-storage generator can be stably controlled to the target value during AFC operation.

On the other hand, if the difference between the rotation speed command value and the actual measurement value is added to the phase command value, the response speed of the active power P control is improved.

In the excitation phase control by the active power command value, the active power command value immediately before the active power command value changes is used,
That is, according to the one in which the active power command value before one sampling is used and the excitation phase is controlled according to the difference between this and the actual power, the change in the phase angle becomes gentle, and the stability of the system is improved. Is preferred.

Further, even during the pumping operation, the electric power required by the system can be efficiently operated, and the economical effect is extremely large.

[Brief description of drawings]

1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing an outline of the principle of a variable speed pumped storage power generation system, and FIG. 3 is a block diagram showing an outline of the system according to the present invention.
FIG. 4 is a waveform diagram showing an example of the relationship between output and efficiency of the Francis turbine, and FIG. 5 is a block diagram showing another embodiment of the present application. E _x ...... exciting circuit, G ₁ ...... variable-speed power generating system, L ...... transmission line, 100 ...... control instruction unit, T ...... operation ends, 1 ...... stator 2 ...... rotor, 3 ...... Slip detector, 4 ... Voltage generator, 5a-5c ... Stator a, b, c phase winding, 6a-6c ... Rotor a, b, c phase winding, 7 ... Rotation speed Measuring unit, 10-system, 11-speed generator, 13-guide vane, 14-opening setting device, 15-command value calculation circuit, 16-secondary winding phase difference angle calculation unit, 17 ...... Secondary winding excitation amount setting unit, 18 ...... Voltage adjustment unit, 19 ...... Current transformer, 20 ...... Voltage transformer, 21 ...... Active power derivation unit, 22a to 22c …… A of secondary excitation , b, c phase winding,
_0: Output command value, N _0: Speed command value, N: Speed, 23
a-23c …… Phase shift section, 24 …… Comparison section, 25 …… Velocity response governor, 26 …… Correction section.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Nohara 3-1-1 Hitachi-machi, Hitachi City Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Masuo Goto 3-1-1 Hitachi-machi, Hitachi City Hitachi Research Laboratory, Hitachi, Ltd. (72) Hidenori Sawa, 5-2-1, Omika-cho, Hitachi City, Ltd., Omika Plant, Hitachi, Ltd. (56) References Japanese Patent Laid-Open No. 59-72998 (JP, A) Kai 55-56499 (JP, A) JP 56-126675 (JP, A) JP 55-10856 (JP, A) JP 53-110017 (JP, A) JP 53-140522 ( JP, A) JP 52-46428 (JP, A) JP 53-32314 (JP, A) JP 59-173000 (JP, A)

Claims (4)

(57) [Claims] 1. A water turbine is connected to an induction machine having a secondary winding connected to a power system, the water turbine is operated at a variable speed of setting, and the secondary winding is driven by electric power of a slip frequency. In the control device of the variable speed pumped storage power generation system including the secondary excitation control, inputting the active power command value of the input and output to the induction machine,
The output value of the water turbine corresponding to the active power command value indicates a rotation speed command value indicating the maximum efficiency, is output according to preset active power and maximum efficiency rotation speed characteristic data, and the actual head is input. Command calculation means (15) for obtaining and outputting a command value of the guide vane opening degree of the water turbine based on the actual head, the active power command value and the command value of the rotation speed, and the command calculation means (15) Comparing means (24) for obtaining the difference between the rotation speed command value and the actual rotation speed of the water turbine, and correction means (25, for correcting the guide vane opening command value so that the difference between the rotation speeds becomes zero or near zero. 26), an opening setting means (14) for outputting the set value of the vane opening to the water turbine control means on the basis of the corrected guide vane opening command value, the active power command value and the actual value of the induction machine. It is necessary to find the difference from the electric power and bring the difference to zero or near zero. And a phase difference angle calculating means (16) for obtaining a phase angle command value of the secondary excitation power, and a voltage adjustment for setting a secondary excitation amount required to make a terminal voltage of the induction machine a reference voltage which is a target of the system. Means (18)
And a secondary winding excitation amount setting means (17) for setting various amounts of excitation power of the secondary winding based on the set secondary excitation amount and the phase angle command value. A control device for a variable speed pumped storage hydropower system, comprising: an excitation means (23) for exciting the secondary winding based on the amount of excitation. 2. A water turbine is connected to an induction machine having a secondary winding connected to an electric power system, the water turbine is operated at a variable rotation speed, and the secondary winding is driven by electric power having a slip frequency. In the control device of the variable speed pumped storage power generation system including the secondary excitation control, inputting the active power command value of the input and output to the induction machine,
The output value of the water turbine corresponding to the active power command value indicates a rotation speed command value indicating the maximum efficiency, is output according to preset active power and maximum efficiency rotation speed characteristic data, and the actual head is input. Command calculation means (15) for obtaining and outputting a command value of the guide vane opening degree of the water turbine based on the actual head, the active power command value and the command value of the rotation speed, and the command calculation means (15) Comparing means (24) for obtaining the difference between the rotation speed command value and the actual rotation speed of the water turbine, and correction means (25, for correcting the guide vane opening command value so that the difference between the rotation speeds becomes zero or near zero. 26), an opening setting means (14) for outputting the set value of the vane opening to the water turbine control means on the basis of the corrected guide vane opening command value, the active power command value and the actual value of the induction machine. Calculate the difference between the electric power and the sum of the difference and the difference in the number of revolutions to zero. Is a phase difference angle calculating means (16) for obtaining a phase angle command value of the secondary excitation power required to bring it to near zero, and a secondary required for setting the terminal voltage of the induction machine to a target reference voltage of the system. Voltage adjustment means to set the amount of excitation (18)
And a secondary winding excitation amount setting means (17) for setting various amounts of excitation power of the secondary winding based on the set secondary excitation amount and the phase angle command value. A control device for a variable speed pumped storage hydropower system, comprising: an excitation means (23) for exciting the secondary winding based on the amount of excitation. 3. The control device for a variable speed pumped storage hydropower system according to claim 2, wherein the active power command value is a power command value immediately before the command value is changed. 4. The control device for a variable speed pumped storage hydropower system according to claim 2, wherein the active power command value is a power command value after the command value is changed.